A class observation day was scheduled to be held in Gaku's class. However, Gaku was worried that if Hayato took a day off to attend, it would cause inconvenience at his workplace and increase his workload.
That's pretty fishy...
Da ist doch was faul.
Qué sospechoso.
Cette attitude est très suspecte.
È un po' sospetto...
Muito suspeito...
Подозрительно.